Respiratory infection in the first year of life and subsequent asthma risk after age 5 years, stratified by gestational age
| Infection stratified by gestational age | Asthma n (%) | No asthma n (%) | HR (95% CI) | p Value | HR* (95% CI) | p Value |
|---|---|---|---|---|---|---|
| Weeks 0–27 | ||||||
| Infection | 52 (20.6) | 200 (79.4) | 2.03 (1.47 to 2.80) | <0.001 | 2.22 (1.59 to 3.09) | <0.001 |
| No infection | 130 (10.6) | 1091 (89.4) | Reference | Reference | ||
| Weeks 28–31 | ||||||
| Infection | 132 (18.3) | 591 (81.7) | 1.47 (1.21 to 1.78) | <0.001 | 1.57 (1.29 to 1.92) | <0.001 |
| No infection | 458 (12.8) | 3130 (87.2) | Reference | Reference | ||
| Weeks 32–36 | ||||||
| Infection | 738 (18.9) | 3168 (81.1) | 1.47 (1.35 to 1.59) | <0.001 | 1.54 (1.42 to 1.68) | <0.001 |
| No infection | 2588 (13.3) | 16 940 (86.7) | Reference | Reference | ||
| Weeks 37–41 | ||||||
| Infection | 6194 (17.8) | 28 645 (82.2) | 1.44 (1.40 to 1.48) | <0.001 | 1.49 (1.45 to 1.53) | <0.001 |
| No infection | 22 075 (12.7) | 152 119 (87.3) | Reference | Reference | ||
| Weeks >41 | ||||||
| Infection | 446 (17.8) | 2061 (82.2) | 1.51 (1.36 to 1.68) | <0.001 | 1.57 (1.41 to 1.75) | <0.001 |
| No infection | 1512 (12.1) | 11 023 (87.9) | Reference | Reference | ||
| Weeks uncertain | ||||||
| Infection | 23 (21.5) | 84 (78.5) | 2.10 (1.29 to 3.42) | 0.003 | 2.21 (1.34 to 3.65) | 0.002 |
| No infection | 56 (10.4) | 482 (89.6) | Reference | Reference | ||
*Adjusted for child's sex, maternal asthma, maternal age at delivery, year of birth, birth weight, maternal smoking, infection during first year of life, parity and chronic lung disease.